just don't buy from BBTS if you don't want a customs charge. they are a great company and good customer service however always declare full value on toys sadly, so they attract customs charges. stick to the uk stockists they are fantastic and should see you right
I have noticed on Amazon UK a couple of Japanese (well, I assume they are) stores listing Takara Generations stuff etc at reasonable prices. Wonder if it's worth a punt?
If you ever buy from BBTS, I'd say it's worth paying the extra for UPS Air delivery. It's often only a few dollars more than the cheapest option. You more than likely will have to pay charges on it, but you can call them to figure out how much it'll be (once the package is in the UK). The big downside is that's it's COD, so the driver will expect you to have the correct money ready, or no box for you.
Except that none of them have Planet X Anything that cuts parcelfarce out of the equation sounds like a good idea.